Why is Johnny the only thing dally loves?

Johnny is the only thing Dally loves because he sees in him a vulnerability and innocence that he himself has lost. Dally has endured a tough life filled with violence and hardship, and Johnny represents a sense of hope and the possibility of a better future. Their bond is deepened by the protective instincts Dally feels towards Johnny, who is often seen as the weaker member of their group. In a world where Dally feels he has nothing, his love for Johnny becomes a source of meaning and connection.